Effect of Methyl Jasmonate on Phenolic Accumulation in Wounded Broccoli.

Yuge Guan,Mengyang Hou,Jiaoxue Yu,Yaru Ji,Aili Jiang,Yongping Xu,Rengaowa Sa,Manru Zhao,Xiaozhe Yang,Ke Feng,Wenzhong Hu

doi:10.3390/molecules24193537

Abstract

In order to find an efficient way for broccoli to increase the phenolic content, this study intended primarily to elucidate the effect of methyl jasmonate (MeJA) treatment on the phenolic accumulation in broccoli. The optimum concentration of MeJA was studied first, and 10 μM MeJA was chosen as the most effective concentration to improve the phenolic content in wounded broccoli. Furthermore, in order to elucidate the effect of methyl jasmonate (MeJA) treatment on phenolic biosynthesis in broccoli, the key enzyme activities of phenylpropanoid metabolism, the total phenolic content (TPC), individual phenolic compounds (PC), antioxidant activity (AOX) and antioxidant metabolism-associated enzyme activities were investigated. Results show that MeJA treatment stimulated phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarin coenzyme A ligase (4CL) enzymes activities in phenylpropanoid metabolism, and inhibited the activity of polyphenol oxidase (PPO), and further accelerated the accumulation of the wound-induced rutin, caffeic acid, and cinnamic acid accumulation, which contributed to the result of the total phenolic content increasing by 34.8% and ferric reducing antioxidant power increasing by 154.9% in broccoli. These results demonstrate that MeJA in combination with wounding stress can induce phenylpropanoid metabolism for the wound-induced phenolic accumulation in broccoli.

Highlights

Broccoli is a well known green vegetable with great commercial value owing to its special nutritional and functional components such as phenolic compounds [1,2], vitamin C (Vit C), and other bioactive compounds (Zn, fiber, glucosinolates, etc.) [3,4]
At 36 h, the maximum value of Total Phenolic Content (TPC) was obtained in 10 μmol L−1 (μM) methyl jasmonate (MeJA)
Our studies showed that low concentration (1 μM) MeJA had little effect on TPC in broccoli during all the storage period, which is probably because the concentration of MeJA was too low to induce the mechanism of resistance to wounding stress

Summary

Introduction

Broccoli is a well known green vegetable with great commercial value owing to its special nutritional and functional components such as phenolic compounds (quercetin, caffeic, quinic acid, chlorogenic acid, etc.) [1,2], vitamin C (Vit C), and other bioactive compounds (Zn, fiber, glucosinolates, etc.) [3,4]. It has been confirmed that wounding stress induces phenolic biosynthesis and enhances antioxidant capacity in various fruit and vegetables, such as carrot [7], potato [8], onion [9], pitaya [10], lettuce [11], celery [11], and sweet potato [11]. These findings indicate that wounding can be used as an effective and practical means to enhance the phenolic accumulation and improve the nutritional quality of the postharvest product.

Methods

Results

Discussion

Conclusion